RALEIGH, N.C. — U.S. Education Secretary Arne Duncan is offering federal cash incentives to achieve one of his priorities: developing national standards for reading and math to replace the current state-by-state hodgepodge of benchmarks.

Duncan said Sunday that the efforts of 46 states to develop common, internationally measured standards for student achievement would be bolstered by up to $350 million in federal funds to help them develop tests to assess those standards.

Duncan made the announcement in Cary, N.C., at a conference for education experts and 20 governors hosted by the National Governors Association and the James B. Hunt, Jr. Institute for Educational Leadership and Policy.

Education decisions generally are controlled by states, and the federal government cannot mandate national standards. That makes for wide variation. Students and schools deemed failing in one state might get passing grades in another.

It will be up to states to adopt new standards. But Duncan has been pushing the effort — and now he's using Washington's checkbook. He said spending up to $350 million to support state efforts to craft assessments would be Washington's largest-ever investment in encouraging a set of common standards.

The money will come from the federal Education Department's $5 billion fund to reward states that adopt innovations the Obama administration supports.

"Historically, this was a third rail. You couldn't even talk about (standards)," Duncan said. "What you've seen over the past couple years is a growing recognition from political leaders, educators, unions, nonprofits — literally every sector — coming to realize that 50 states doing their own thing doesn't make sense."

Every state except Alaska, South Carolina, Missouri and Texas has signed on to an effort by the National Governors Association and Council of Chief State School Officers. But getting the states to adopt whatever emerges will be politically difficult.

"Resources are important, but resources are actually a small piece of this puzzle," Duncan said. "What's really needed here is political courage. We need governors to continue to invest their energy and political capital."

Any tests developed for the new standards likely would replace existing ones. Asked to explain the money's focus on developing more tests, Duncan said developing the standards themselves would be relatively inexpensive.

Developing assessments, by contrast, is a "very heavy lift financially," he said, expressing concern that the project could stall without federal backing.

"Having real high standards is important, but behind that, I think in this country we have too many bad tests," Duncan said. "If we're going to have world-class international standards, we need to have world-class evaluations behind them."